1. Field of the Invention
The present invention relates to an image forming apparatus having a human-body communication function and a method for authentication in the image forming apparatus and, more particularly, to a technique for performing authentication using human-body communication.
2. Description of the Related Art
For the sake of efficiently performing tasks, there has been widespread use of a multi function peripheral (hereinafter, also referred to as MFP) having a plurality of functions, such as a printing function, a copying function, a facsimile function, and a scanning function. Such MFP may be caused to execute jobs of different functions (for example, a printing job and a facsimile transmission job) in parallel.
By the way, in offices and the like, there are needs for restricting the function allowed to be used, out of the functions provided in MFP, according to the contents of tasks for each user. For example, the use of all the functions is allowed for a user, whereas only a copying function is allowed for another user.
In order to provide such management, there have been employed mechanism for performing user authentication in MFP as well as for allowing the use of pre-defined functions, based on the result of the user authentication. In order to implement such user authentication, it is common to employ methods which require users to input a password.
As a user authentication method, instead of such methods requiring inputting of a password, there have also been proposed a method which requires each user to mount, to an MFP main body, a magnetic card or a memory unit storing his or her own user ID, before he or she operates the MFP.
Alternatively, there have been proposed a method which causes each user to carry a storage medium capable of wireless communication, such as an RFID (Radio Frequency IDentification) card or a non-contact type IC (Integrated Circuit) card (or a portable device incorporating a non-contact type IC card) and also causes an MFP to receive a user ID from the storage medium carried by the user within a predetermined area for performing user authentication. For example, Japanese Laid-Open Patent Publication No. 2007-137211 discloses a structure adapted such that, when a touch sensor detects a touch of a human-body on an operation knob of an engine activation switch, this will start an authentication operation in cooperation with an electronic key.
Further, as a method with improved security, there have been proposed a method which utilizes biometric authentication, such as fingerprint authentication and vein pattern authentication. For example, Japanese Laid-Open Patent Publication No. 2002-278938 discloses a structure which detects, as characteristic information, a change in electric resistance at a button position which is touched by a finger when the button is clicked and a change in three-dimensional shape of a palm covering the upper surface of a mouse when the mouse is clicked and, based on the characteristic information, performs authentication.
Further, Japanese Laid-Open Patent Publication Nos. 2001-195368 and 2002-222169 propose use of human-body communication for user authentication.
As described above, an MFP is capable of executing a plurality of functions in parallel, which may cause a plurality of users to generate commands for different functions to the MFP. In this case, there is a need for performing user authentication, at least on a function-by-function basis.
In dealing with the aforementioned needs, with the method which requires inputting of a password, users are required to input a password every time each user generates a command for a function, which is very cumbersome. Further, with the method which uses a magnetic card or a memory unit, it is necessary to provide the same number of reading devices as the number of users who can use the MFP at the same time, which complicates the structure and increases the cost. Further, with the method which uses a storage medium capable of wireless communication, it is impossible to identify which user has generated the command, when a plurality of storage media exist within the same communication area.
Further, the methods disclosed in Japanese Laid-Open Patent Publication Nos. 2001-195368 and 2002-222169 do not suggest performing further authentication once a successful user authentication has been made, and therefore, these methods do not satisfy the aforementioned needs for user authentication on a function-by-function basis as mentioned above.